Energy is transmitted by waves. Patterns in transmitted energy waves are used to form images of the object from which the energy waves originate. Energy waves in the form of light enable the formation of the visual image of an object by the human eye. Non-optical energy waves may also be used to form images of objects such as the imaging of underground mineral deposits with seismic wave patterns.
In order to obtain an accurate representation of the object being imaged, it has become necessary to develop techniques to improve the resolution and contrast of the images produced by recording wave patterns. These techniques have been applied to the coherent recording of wave patterns produced over the spectrum of recognizable energy waves. However, for simplicity of disclosure, the following description will center on light waves. More specifically, and for the purpose of illustrating the improvement in the coherent recording of wave patterns, the following disclosure will center on holography and the production of holographic images using holograms.
In recent years, holographic techniques have been used with light energy waves to produce holographic images. While holography has added new dimensions to the imaging of objects, it is not without its problems.
The original and most basic form of holography, the in-line or Gabor type, has the distinct advantage that it requires no lenses or mirrors.
One of the main detractors from the quality of in-line holographic images is the so-called "twin image" problem. The twin image problem appears when one image in the reconstruction of a virtual holographic image is confused by the out-of-focus twin image. Despite the twin image problem, in-line holograms have achieved limited acceptance, particularly in areas involving the sizing of small particles and velocimetry, such as in examining turbulent flow patterns of liquids. However, to be able to expand on the tremendous imaging potential offered by holographic techniques, there remains in the art a need to improve upon the resolution and contrast of all types of holographic images.
One attempt at resolving the problem of the lack of acceptable resolution and contrast in holographic images involves digitizing the hologram and then using digital reprocessing techniques to improve the resolution and contrast of the reconstructed hologram. The drawback to such digital reprocessing techniques is that an a priori knowledge of the subject is required. Thus, if prior knowledge of the subject is nonexistent, such digital reprocessing techniques are useless.
Therefore, a need remains in the art to find a system for improving, in particular, the resolution and contrast problems associated with making maximum use of holographic imaging techniques; but, more generally, to improve the resolution and contrast of images associated with coherent recordings created by a variety of other energy waves.